Investigating Paramutation at the Maize b1 Gene: Molecular Mechanisms of Heritable Epigenetic Gene Regulation

智力优势：一个人的基因如何被激活或沉默是一个影响生物学所有领域的基本问题。基因表达模式，即在不同的组织和发育过程中，哪些基因是开启的，哪些是关闭的，在每个物种的个体中都是高度可复制的，这些模式每一代都能有效地重置。这些遗传规则的一个例外是玉米的参数化。参数化导致某些基因沉默，当基因传递给后代时，这种沉默被保留下来。根据哪些基因被沉默，可以观察到植物生长和发育的巨大变化。先前的研究表明，这些基因表达的可遗传变化是由RNA介导的，这表明RNA不仅仅是DNA指令的载体；它能够发出自己的指令，改变下一代基因的表达方式。这个项目是表征参数化所需的一个基因，mop3（参数化的中介）。初步研究表明，相对于其他先前表征的参数化所需的基因，mop3在RNA介导的基因沉默中起着不同的作用。因此，从对mop3的进一步研究以及从参数化所需的其他基因的分离和表征中获得新的机制见解，这是本项目的另一个主要目标。了解基因表达的遗传变化机制将为植物如何调节对环境变化的适应性反应提供新的见解。更广泛的影响：该项目的研究人员长期致力于培训和推广。在过去的12年里，有5名博士后、8名研究生、45名本科生、10名高中生和5名高中教师参与了研究工作，这些研究工作产生了构成本项目基础的数据。目前的研究项目每年将为两名本科生和一名高中教师及其学生提供培训。高中教师将参加每年的暑期实习，包括直接参与实验和设计课程，以吸引高中学生在学年。教师将与其他教师一起参与一个广泛的网络，这样每个人的课程创新都可以被分享，从而有助于提高更多学生的科学素养。

Intellectual Merit:How an individual's genes are activated or silenced is an essential question impacting all fields of biology. Gene expression patterns, i.e. which genes are on and which are off in different tissues and during development, are highly reproducible among individuals of each species and those patterns are efficiently reset every generation. One exception to these genetic rules is paramutation in maize. Paramutation leads to certain genes becoming silenced and that silencing is retained when the genes are transmitted to offspring. Depending on which genes are silenced dramatic changes in the plant's growth and development can be observed. Prior work has demonstrated that these heritable changes in gene expression are mediated by RNA, demonstrating RNA is not just a vehicle for DNA's commands; it is able to issue its own commands that alter how genes are expressed in the next generation. This project is to characterize a gene that is required for paramutation, mop3 (mediator of paramutation3). Initial research has demonstrated that mop3 acts at a distinct step in RNA mediated gene silencing relative to other previously characterized genes required for paramutation. Thus, new mechanistic insights should be gained from further study of mop3 as well as from the isolation and characterization of additional genes required for paramutation, another major goal of this project. Understanding mechanisms for heritable changes in gene expression will provide new insights into how plants might mediate adaptive responses to a changing environment. Broader Impacts: The investigators for this project have had a long standing commitment to training and outreach. During the past 12 years, 5 postdoctoral fellows, 8 graduate students, 45 undergraduate students, 10 high school students and 5 high school teachers have participated in the research efforts that generated the data that formed the basis for this project. The current research project will provide training for two undergraduate students each year and a high school teacher and her students. The high school teacher will participate in a summer internship each year that will involve direct participation in the experiments and designing curriculum to engage the high school students during the academic year. The teacher will participate in a broad network with other teachers so that each person's curriculum innovation can be shared and thus, contribute to an increase in the science literacy of a larger number of students.